A 56-year-old man presents for a routine check-up. He has a…

A 56-year-old man presents for a routine check-up. He has a 40-pack-year smoking history and currently smokes. You are reviewing lung cancer screening recommendations. According to the American College of Chest Physicians (ACCP) guidelines, annual screening with low-dose CT for lung cancer should occur in 50 to 80 year-old smokers with a smoking history of at least ______ pack-years.